The present invention relates to an electromagnetic valve, and more particularly to an electromagnetic valve for use with hydraulic braking systems and slip controls.
In conventionally used electromagnetic valves of the type as disclosed, for example, by DE-OS 37 29 216, valve sleeves are inserted in a valve casing or housing configured as a steel valve block, and caulked therein. When using magnetic valves closed in a de-energized basic condition, the valve sleeve forms the actual magnetic core of a magnet coil. Located in the interior of the valve sleeve is a hold-on magnet which actuates a valve needle, along with a guide thereof. However, when using electromagnetic valves open in a de-energized basic condition, it is a bushing inserted at the point where the valve sleeve is caulked to the valve casing that operates as the magnetic core.
The caulking, impressed with the aid of a tool in a substantially nose-type form in the valve block casing, will then establish a connection through frictional resistance to the valve sleeve clamped between the valve casing and the bushing.
It is especially under consideration of the relatively high hydraulic test pressures within the valve sleeve, that the conventional caulking of the valve sleeve within the valve casing is considered to require improvement to prevent the valve sleeve from slipping out and the valve casing from being damaged as a result of enhanced shear stress between the faces of contact. In addition, the direct fixation of the valve sleeve within the valve casing requires employment of tough and high-strength steels that can be correspondingly reshaped. Moreover, the high-precision manufacturing of a casing bore of the valve casing and the precise orientation of the valve needle by means of a centering member within the casing bore vis-A-vis a valve seat, as well as the force-locking fixation of the centering member are considered as requiring substantial efforts.
It is, therefore, an object of the present invention to provide an easy-to-manufacture electromagnetic valve comprising a self-centering means of the valve needle over the valve seat and enabling a particularly safe, high-loadable and tight attachment of the valve sleeve within a valve-accommodating member. Another object of the invention is the low-cost manufacture of a pressure fluid supply to the electromagnetic valve.